This article approaches the problem of organizing Romanticism and, with it, the nineteenth century by way of exploring a new type of ontological thinking, introduced by the Romantics, specifically Hölderlin, and designated here as “Romantic ontology.” This ontology is defined by the impossibility of capturing the ultimate workings of the world by any given concept, which only allows us an access to certain effects of these ultimate workings. The radical limitations thus established do not inhibit but instead help to advance thought and knowledge and make them succeed where they failed previously, including in developing a better understanding of Romantic and nineteenth-century literature and culture. The nature of thought and knowledge changes, however: the unthinkable and the unknowable are now irreducible at any stage of our thinking and knowledge. As a result, we are irreducibly deprived of certainty, and the recourse to probability becomes an unavoidable aspect of our thinking and knowledge. Accordingly, we can only estimate and argue for the probability of our historical and theoretical claims, for example, those concerning how Romanticism and the nineteenth century were organized by a given figure or community at the time, or how they could be organized by us. This, however, is thought and knowledge, too, and they may be the best we can have.